Combining multiple Swagger+APIGW using jq

base.yml

---
  swagger: 2.0
  basePath: /prod
  info:
    title: AwsSamExample
  bschemes:
  - https
  paths:
    /:
      x-amazon-apigateway-any-method:
        produces:
        - application/json
        responses:
            '200':
            description: 200 response
            schema:
                $ref: "#/definitions/Empty"

commands.sh

# Install jq
brew install jq

# Install PyYAML
pip install pyyaml

# Converts the YAML files to JSON
python -c 'import sys, yaml, json; json.dump(yaml.load(sys.stdin), sys.stdout, indent=2)' < base.yml > base.json
python -c 'import sys, yaml, json; json.dump(yaml.load(sys.stdin), sys.stdout, indent=2)' < ext.yml > ext.json

# Merges both json files into a single json
jq -s '.[0] * .[1]' ext.json base.json > final.json

# Converts the final json file back to yaml
python -c 'import sys, yaml, json; yaml.dump(json.load(sys.stdin), sys.stdout, indent=2)' < final.json > final.yml

ext.yml

---
  paths:
    /:
      x-amazon-apigateway-integration:
        responses:
          default:
              statusCode: 200
        # NOTE: ${LambdaFunction} must match the Lambda resourcename
        uri:
          Fn::Sub: "arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${LambdaFunction.Arn}/invocations"

        passthroughBehavior: when_no_match
        httpMethod: POST
        type: aws_proxy

final.yml

swagger: 2
basePath: /prod
bschemes: [https]
info: {title: AwsSamExample}
paths:
  /:
    x-amazon-apigateway-any-method:
      produces: [application/json]
      responses:
        '200': null
        description: 200 response
        schema: {$ref: '#/definitions/Empty'}
    x-amazon-apigateway-integration:
      httpMethod: POST
      passthroughBehavior: when_no_match
      responses:
        default: {statusCode: 200}
      type: aws_proxy
      uri: {'Fn::Sub': 'arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${LambdaFunction.Arn}/invocations'}